Last Updated: 25/10/2018
AGM stands for ‘Absorbent Glass Matt’ and they have the acid solution soaked into material between the lead plates rather than a traditional flooded construction. This results in a battery which is totally spill proof and produces excellent recharge cycles.
These batteries were first used by airlines in the 1970's to provide onboard power and to replace the wet lead acid systems which had proved unsafe. As manufacturing costs came down this technology was applied to mass produced leisure batteries and they are now popular options.
As with standard lead acid batteries these AGM batteries come in both dual-purpose and semi-traction options with some types requiring venting.
AH stands for Ampere Hours and relates to the battery's ability to provide power over certain periods of time, the higher the AH then the longer the battery will be able to provide power. Battery AH typically increases with actual physical battery size and it is important to strike a balance between the right size battery in terms AH with your actual power requirements and physical size restrictions.
There is a great deal of mis-information associated with Calcium Technology, to put the record straight the technique is used in most, if not all, modern battery production. The technology is based upon strengthening the lead plates with Calcium and other materials to make them stronger. They do not require different charging voltages and should always be treated as standard lead acid batteries.
Ultimately capacity refers to how long a battery will last for, but with no formal requirement to list capacity in an universally accepted way, a new European system is being championed by a number of leading manufacturers and this is a system we have also adopted.
The rating is based on three different power ratings over different time periods, for example:
- 85AH @ 5 Hours
- 100AH @ 20 Hours
- 110AH @ 100 Hours
Effectively the above ratings indicate that this product would produce 110AH over a long discharge period, but only 85AH over a shorter space of time.
CCA stands for Cold Cranking Amps and relates to the battery's ability to turn an engine over. If you don't intend to turn an engine over then you can safely ignore the CCA rating and focus instead on AH. If you intend to use your battery for starting as well as general leisure use then then look for a higher CCA rating, dual-purpose leisure batteries tend to lend themselves better for this application.
Cycle / Deep Cycle
A cycle is the number of times a battery can be part discharged by 50% then recharged. The more cycles a battery can do then the longer the battery should last in the long term, with these products usually termed 'deep-cycle' batteries.
To help with discharge levels here is the relation to the percentage of charge and voltage:
- 12.69 Volts or above = 100% Charged
- 12.5 Volts = 75% Charged
- 12.2 Volts = 50% Charged
- 12.00 Volts = 25% Charged
- Below 12.00 Volts = 0% Charged (Discharged)
The above can be particularly useful if you have a battery tester to hand.
GEL based batteries have the acid solution contained in a gel type paste rather than flooded or soaked on matt. Generally they tend to be more suited to electric vehicle applications but are ideal options for the most demanding situations such as for solar and other backup power systems.
GEL batteries offer the most recharge cycles of the typical leisure battery technologies, but the range is limited to only a small number of manufacturers and battery types.
Lead Acid Batteries
This is the most common type of construction in both dual-purpose and semi-traction leisure batteries. Inside the battery is a solution of water and acid which cover the internal lead plates and they come in sealed and semi-sealed options.
Sealed variants have no function to access the cells and require no topping up sometimes referred to as 'maintenance free', semi sealed batteries provide access via six caps on the top of the battery which can be removed to top up the acid levels. Under normal conditions you will never need to access the cells on a leisure battery, however frequent use and deep discharging will cause the solution to evaporate.
Lead acid batteries need to breathe and should never be kept in airtight boxes, they will always have a breather hole on the side which you can attach a vent pipe to for peace of mind.
The voltage is essentially what moves the current around the battery and the majority of our leisure batteries are 12v which will match most if not all modern leisure battery applications. A small number of semi-traction batteries, such as those by Trojan, also come in a 6v range allowing for the creation of large battery banks.